Method of producing plastic pyrolysis products from a mixed plastics stream

ABSTRACT

Method of producing pyrolysis products from a mixed plastics stream along with an associated system for processing mixed plastics. The method includes conducting pyrolysis of a plastic feedstock to produce a stream of plastic pyrolysis oil; feeding the plastic pyrolysis oil to an aromatization unit having an aromatization reactor with an aromatization catalyst disposed therein to generate an aromatics rich stream; and passing the aromatics rich stream to an aromatic recovery complex to separate the aromatics rich stream into a BTX fraction, a gasoline blending fraction, a gas fraction comprising hydrogen and C1-C4 hydrocarbons, and an aromatic bottoms fraction comprising hydrocarbons boiling above 180° C., where the BTX fraction consists of benzene, toluene and mixed xylenes and the gasoline blending fraction comprises aliphatic hydrocarbons with a boiling range from C5 hydrocarbon up to the aromatic bottoms fraction.

TECHNICAL FIELD

The present disclosure relates to method of producing pyrolysis productsfrom a mixed plastics stream. In particular, certain embodiments of thedisclosure relate to methods to producing aromatics from waste plasticfeedstock.

BACKGROUND

Plastic is a synthetic or semisynthetic organic polymer composed ofmainly carbon and hydrogen. Further, plastics tend to be durable, with aslow rate of degradation, therefore they stay in the environment for along time and are not prone to rapid breakdown upon disposal. Pureplastics are generally insoluble in water and nontoxic. However,additives used in plastic preparation are toxic and may leach into theenvironment. Examples of toxic additives include phthalates. Othertypical additives include fillers, colorant, plasticizers, stabilizers,anti-oxidants, flame retardants, ultraviolet (UV) light absorbers,antistatic agents, blowing agents, lubricants used during itspreparation to change its composition and properties.

Plastics pyrolyze at high temperatures and can be converted back totheir original monomers as gas or liquid and can be recovered. However,the additives added to the plastic during production present challengesin effectively utilizing the recovered products from pyrolysis. Uponpyrolysis, the additives end-up in the pyrolysis products.

SUMMARY

Accordingly, there is a clear and long-standing need to provide asolution to utilize the pyrolysis products generated from the pyrolysisof plastics. To utilize such pyrolysis products the residue left fromthe additives in the pyrolysis product must be removed or the pyrolysisproducts utilized in a manner that the residue is not destructive.

The generated pyrolysis products comprise a substantial portion ofnaphtha and other hydrocarbon streams which are desirably able to beimplemented as feed streams to existing or new refining processes. Thetransformation of light naphtha or C5-C6 streams, which originates fromrefinery and gas plants, into value-added gasoline blending componentshas been an ongoing challenge to researchers in academia and industry.The primary use for light naphtha is as feed for steam crackers or theproduction of olefins such as ethylene, propylene, and butenes and as ablending stock for gasoline production. However, the light naphthastream has become an undesirable gasoline blending component because ofits low octane number and high vapor pressure. This challenge has ledrefiners to seek options to upgrade this low-value stream into highervalue products.

The transformation of light naphtha has been hindered by inertness ofcarbon-carbon and carbon-hydrogen bonds, which results in an elevatedtemperature and, therefore, unfavorable thermodynamics, low selectivityand yields, generally result in high cost for commercial applications.However, the current global demand for gasoline is 26.1 million barrelsper day (bpd) or about 26% of global refined products demand with globalgasoline demand expected to continue an average annual growth rate of2.3%. The gasoline pool receives product streams, such as isomerate,reformate, alkylate, and fluid catalytic cracking (FCC) gasoline, fromdifferent units in the refinery as well as the addition of renewableoxygenates. The composition of gasoline comprises different compounds ofparaffins, isoparaffins, olefins, naphthenes, and aromatics, known asPIONA. As such, it is desirable to process the products generated fromthe pyrolysis of plastics into gasoline replacements or blendingstreams. One solution is to process the products generated from thepyrolysis of plastics through aromatization to convert the naphtha anddistillate components of the generated plastic pyrolysis oil intoaromatics.

In accordance with one or more embodiments of the present disclosure, amethod of producing pyrolysis products from a mixed plastics stream isdisclosed. The method includes (a) conducting pyrolysis of a plasticfeedstock to produce a stream of plastic pyrolysis oil; (b) feeding theplastic pyrolysis oil to an aromatization unit having an aromatizationreactor with an aromatization catalyst disposed therein to generate anaromatics rich stream; and (c) passing the aromatics rich stream to anaromatics recovery complex to separate the aromatic rich stream into aBTX fraction, a gasoline blending fraction, a gas fraction includinghydrogen and C1-C4 hydrocarbons, and an aromatic bottoms fractionincluding hydrocarbons boiling above 180° C. The BTX fraction consistsof benzene, toluene and mixed xylenes and the gasoline blending fractionincludes aliphatic hydrocarbons with a boiling range from C5hydrocarbons up to the aromatic bottoms fraction.

In some embodiments, a first fractionator separates the plasticpyrolysis oil into a first distillate fraction comprising hydrocarbonsboiling in the range of 36 to 370° C. and a residual heavy fractioncomprising hydrocarbons boiling above 370° C., and the first distillatefraction is fed to the aromatization unit in lieu of an entirety of theplastic pyrolysis oil.

In some embodiments, the first fractionator further separates the firstdistillate fraction into a plastic pyrolysis naphtha stream and aplastic pyrolysis second distillate stream; and the aromatization unitis split into a naphtha aromatization unit having a naphthaaromatization reactor fed by the plastic pyrolysis naphtha stream and asecond distillate aromatization unit having a second distillatearomatization reactor fed by the plastic pyrolysis second distillatestream.

In some embodiments, each aromatization unit further includes aselective hydrogenation unit configured and operated to removedi-olefins by hydrogenation to generate a dediolefinized stream forprovision to the aromatization reactor provided in each aromatizationunit.

In accordance with one or more embodiments of the present disclosure, asystem for processing mixed plastics into plastic pyrolysis products isdisclosed. The system includes an inlet stream comprising mixedplastics: a plastic pyrolysis unit, the plastic pyrolysis unit in fluidcommunication with the inlet stream, and operable to generate a streamof plastic pyrolysis oil from the inlet stream; an aromatization unit influid communication with the stream of plastic pyrolysis oil, thearomatization unit having an aromatization reactor with an aromatizationcatalyst disposed therein operable to generate an aromatics rich stream;and an aromatics recovery complex in fluid communication with thearomatics rich stream, the aromatics recovery complex operable toseparate the aromatic rich stream into a BTX fraction, a gasolineblending fraction, a gas fraction formed from hydrogen and C1-C4hydrocarbons, and an aromatic bottom fraction formed from hydrocarbonsboiling above 180° C. The BTX fraction consists of benzene, toluene andmixed xylenes and the gasoline blending fraction includes aliphatichydrocarbons with a boiling range from C5 hydrocarbons up to thearomatic bottoms fraction.

In some embodiments, a first fractionator is further provided. The firstfractionator is in fluid communication with the stream of plasticpyrolysis oil and separates the plastic pyrolysis oil into a firstdistillate fraction formed from hydrocarbons boiling in the range of 36to 370° C. and a residual heavy fraction formed from hydrocarbonsboiling above 370° C., with the first distillate fraction in fluidcommunication with the aromatization unit in lieu of an entirety of thestream of plastic pyrolysis oil.

In some embodiments, the first fractionator further separates the firstdistillate fraction into a plastic pyrolysis naphtha stream and aplastic pyrolysis second distillate stream; and the aromatization unitis split into a naphtha aromatization unit having a naphthaaromatization reactor and a second distillate aromatization unit havinga second distillate aromatization reactor.

In some embodiments, each aromatization unit further includes aselective hydrogenation unit configured and operated to removedi-olefins by hydrogenation to generate a dediolefinized stream forprovision to the aromatization reactor provided in each aromatizationunit.

Additional features and advantages of the described embodiments will beset forth in the detailed description that follows. The additionalfeatures and advantages of the described embodiments will be, in part,readily apparent to those skilled in the art from that description orrecognized by practicing the described embodiments, including thedetailed description that follows as well as the drawings and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings in which:

FIG. 1 is a schematic illustration of one or more embodiments of thepresent disclosure, in which plastic pyrolysis oil produced in thepyrolysis of a plastic feedstock is fed directly to a unitaryaromatization unit comprising an aromatization reactor;

FIG. 2 is a schematic illustration of one or more embodiments of thepresent disclosure, in which a first distillate fraction which includeshydrocarbons boiling in the range of 36 to 370° C. fractionated fromplastic pyrolysis oil produced in the pyrolysis of a plastic feedstockis fed to a unitary aromatization unit comprising an aromatizationreactor;

FIG. 3 is a schematic illustration of one or more embodiments of thepresent disclosure, in which a first distillate fraction which includeshydrocarbons boiling in the range of 36 to 370° C. fractionated fromplastic pyrolysis oil produced in the pyrolysis of a plastic feedstockis fed to a unitary aromatization unit comprising a selectivehydrogenation unit and an aromatization reactor; and

FIG. 4 is a schematic illustration of one or more embodiments of thepresent disclosure, in which a plastic pyrolysis naphtha stream whichincludes hydrocarbons boiling in the range of 36 to 110° C. and aplastic pyrolysis second distillate stream which includes hydrocarbonsboiling in the range of 110 to 370° C. fractionated from plasticpyrolysis oil produced in the pyrolysis of a plastic feedstock are fedto parallel aromatization units, each comprising a selectivehydrogenation unit and an aromatization reactor.

Reference will now be made in greater detail to various embodiments,some embodiments of which are illustrated in the accompanying drawings.Whenever possible, the same reference numerals will be used throughoutthe drawings to refer to the same or similar units.

DETAILED DESCRIPTION

Embodiments of systems and associated methods for producing pyrolysisproducts from a mixed plastics stream are provided in the presentdisclosure.

A system for processing mixed plastics into plastic pyrolysis productsincludes an inlet stream comprising mixed plastics, a plastic pyrolysisunit, an aromatization unit, and an aromatic recovery complex. Theplastic pyrolysis unit is provided in fluid communication with the inletstream and is operable to generate a stream of plastic pyrolysis oilfrom the inlet stream. The aromatization unit is provided in fluidcommunication with the stream of plastic pyrolysis oil. Further, thearomatization unit is operable to generate an aromatic rich stream andincludes an aromatization reactor with an aromatization catalystdisposed therein. The aromatic recovery complex is provided in fluidcommunication with the aromatic rich stream and is operable to separatethe aromatic rich stream into a BTX fraction, a gasoline blendingfraction, a gas fraction, and an aromatic bottoms fraction comprisinghydrocarbons boiling above 180° C. The BTX fraction consists of benzene,toluene and mixed xylenes and the gasoline blending fraction comprisesaliphatic hydrocarbons with a boiling range from C5 hydrocarbons up tothe aromatic bottoms fraction.

The associated method of producing pyrolysis products from a mixedplastics stream includes conducting pyrolysis of a plastic feedstock toproduce a stream of plastic pyrolysis oil, feeding the plastic pyrolysisoil to an aromatization unit comprising an aromatization reactor with anaromatization catalyst disposed therein to generate an aromatics richstream, and passing the aromatics rich stream to an aromatics recoverycomplex to separate the aromatic rich stream into a BTX fraction, agasoline blending fraction, a gas fraction comprising hydrogen and C1-C4hydrocarbons, and an aromatic bottoms fraction comprising hydrocarbonsboiling above 180° C. The BTX fraction consists of benzene, toluene andmixed xylenes and the gasoline blending fraction comprises aliphatichydrocarbons with a boiling range from C5 hydrocarbons up to aromaticbottoms fraction.

Having generally described the system and associated methods ofproducing pyrolysis products from a mixed plastics stream, embodimentsof the same are described in further detail and with reference to thevarious Figures.

Referring first to FIG. 1 , a schematic illustration of one or moreembodiments of the present disclosure in which a plastic pyrolysis oilproduced in the pyrolysis of a plastic feedstock is fed to anaromatization unit is presented. An inlet stream 101 comprising mixedplastics is provided to a plastic pyrolysis unit 151. The plasticpyrolysis unit 151 is in fluid communication with the inlet stream 101and is operable to generate a stream of plastic pyrolysis oil 102 fromthe inlet stream 101. An aromatization unit 154 is in fluidcommunication with the plastic pyrolysis unit 151 and the stream ofplastic pyrolysis oil 102 and is operable to generate an aromatic richstream 107 of aromatized plastic pyrolysis oil. Additionally, anaromatic recovery complex 157 is in fluid communication with thearomatization unit 154 the aromatics rich stream 107 and is operable toseparate the aromatics rich stream 107 into a BTX fraction 109, agasoline blending fraction 110, a gas fraction 108 comprising hydrogenand C1-C4 hydrocarbons, and an aromatic bottoms fraction 111 comprisinghydrocarbons boiling above 180° C.

Plastic Feedstock

In one or more embodiments, the inlet stream 101 comprises a plasticfeedstock including mixed plastics of differing compositions. Theplastic feedstock provided to the plastic pyrolysis unit 151 may be amixture of plastics from various polymer families. In variousembodiments, the plastic feedstock may comprise plastics representativeof one or more of the polymer families disclosed in Table 1.Specifically, the plastic feedstock may comprise plastics representativeof one or more of polymer families such as olefins polymers, carbonatespolymers, aromatics polymers, sulfones polymers, fluorinated hydrocarbonpolymers, chlorinated hydrocarbon polymers, and acrylonitriles polymers.Further, the plastic feedstock provided to the plastic pyrolysis unit151 may be a mixture of high density polyethylene (HDPE, for example, adensity of about 0.93 to 0.97 grams per cubic centimeter (g/cm³), lowdensity polyethylene (LDPE, for example, about 0.910 g/cm³ to 0.940g/cm³), polypropylene (PP), linear low density polyethylene (LLDPE),polystyrene (PS), polyethylene terephthalate (PET). It will beappreciated that utilization of the mixed plastics feedstock allows forrecycling of plastics without necessitating fine sorting of theplastics.

TABLE 1 Example Polymers Polymer Melting family Example polymer Point, °C. Structure Olefins Polyethylene (PE) 115-135

Olefins Polypropylene (PP) 115-135

carbonates diphenylcarbonate  83

aromatics Polystyrene (PS) 240

Sulfones Polyether sulfone 227-238

Fluorinated hydrocarbons Polytetrafluoroethylene (PTFE) 327

Chlorinated hydrocarbons Polyvinyl chloride (PVC) 100-260

Acrylonitriles Polyacrylonitrile (PAN) 300

The plastics of the inlet stream 101 may be provided in a variety ofdifferent forms. The plastics may be in the form of a powder in smallerscale operations. The plastics may be in the form of pellets, such asthose with a particle size of from 1 to 5 millimeter (mm) for largerscale operations. In further embodiments, the plastics may be providedas a chopped or ground product. Further, the plastics of the inletstream 101 may be natural, synthetic or semi-synthetic polymers. Invarious embodiments, the plastics of the inlet stream 101 may comprisewaste plastics, manufacturing off-spec products, new plastic products,unused plastic products, as well as their combinations.

Plastic Pyrolysis

The plastic pyrolysis unit 151 converts the inlet stream 101 of plasticsto gaseous and liquid products. The liquid products are provided as aneffluent from the plastic pyrolysis unit 151 as the stream of plasticpyrolysis oil 102. The stream of gaseous products is generically shownin each of FIGS. 1, 2, 3, and 4 as off-gas stream 111. The gaseousproducts in the off-gas stream 111 may include various species such ashydrogen and hydrocarbon gases (C1-C4), carbon monoxide (CO), carbondioxide (CO₂), and other acid gases.

The specific reactor used as the plastic pyrolysis unit 151 can be ofdifferent types and are not limited for the purposes of the presentdisclosure. One skilled in the art will appreciate that typical reactortypes that can be used to serve the function of the plastic pyrolysisunit 151 are tank reactors, rotary kilns, packed beds, bubbling andcirculating fluidized bed, ebullated-bed, and others. In one or moreembodiments, the pyrolysis of the plastic feedstock in the inlet stream101 is performed in the presence or absence of a catalyst at atemperature of 300 to 1000° C. In various further embodiments, theplastic pyrolysis unit 151 may operate at a low severity at atemperature less than or equal to 450° C., at a high severity at atemperature greater than 450° C., at a temperature of 300 to 450° C., ata temperature of 450 to 1000° C., at a temperature of 450 to 750° C., ata temperature of 600 to 1000° C., or at a temperature of 750 to 1000° C.In various embodiments, the plastic pyrolysis unit 151 may operate at apressure in the range of 1 to 100 bars, 1 to 50 bars, 1 to 25 bars, or 1to 10 bars. Further, in various embodiments, the residence time of theplastic feedstock in the plastic pyrolysis unit 151 may be 1 to 3600seconds, 60 to 1800 seconds, or 60 to 900 seconds.

In one or more embodiments, stream of plastic pyrolysis oil 102 exitingthe plastic pyrolysis unit 151 may be mixed with refinery fractions.Specifically, the composition of plastic oil in the stream of plasticpyrolysis oil 102 as fed to the first fractionator 152 may vary from 0.1weight percent (wt. %) to 100 wt. % with the remainder comprisingconventional refinery streams. In various embodiments, the compositionof plastic oil in the stream of plastic pyrolysis oil 102 as fed to thefirst fractionator 152 may comprise 1 to 100 wt. % plastic oil, 20 to100 wt. % plastic oil, 40 to 100 wt. % plastic oil, 60 to 100 wt. %plastic oil, 80 to 100 wt. % plastic oil, or substantially 100 wt. %plastic oil.

First Fractionator

With reference to FIGS. 2 and 3 , in one or more embodiments, a firstfractionator 152 is provided to separate the stream of plastic pyrolysisoil 102 into a first distillate fraction 103 and a residual heavyfraction 104. The first fractionator 152 is provided in fluidcommunication with the plastic pyrolysis unit 151 and the stream ofplastic pyrolysis oil 102. As such, the first fractionator 152 is alsoprovided in fluid communication with the aromatization unit 154 and thefirst distillate fraction 103 is provided to the aromatization unit 154in lieu of an entirety of the stream of plastic pyrolysis oil 102.

With reference to FIG. 4 , in one or more embodiments, the firstfractionator 152 is provided to separate the stream of plastic pyrolysisoil 102 into a plastic pyrolysis naphtha stream 203, a plastic pyrolysissecond distillate stream 303, and the residual heavy fraction 104. Assuch, the plastic pyrolysis naphtha stream 203 and the plastic pyrolysissecond distillate stream 303 are provided to the aromatization unit 154in lieu of an entirety of the stream of plastic pyrolysis oil 102.

The first fractionator 152 may comprise any unit operation or systemknown to those skilled in the art for separating a hydrocarbon stream byvapor pressure. An example fractionation unit is an atmosphericdistillation unit. An atmospheric distillation unit utilizes fractionaldistillation by heating the feed to a temperature at which one or morefractions of the mixture will vaporize while leaving other fractions asliquid to separate the feed stream. Further, in various embodiments, thefirst fractionator 152 may be a simple flash column or true boilingpoint distillation with at least 15 theoretical plates. In one or moreembodiments and with reference to FIGS. 2 and 3 , the first fractionator152 separates the stream of plastic pyrolysis oil 102 into the firstdistillate fraction 103 including hydrocarbons boiling in the range of36 to 370° C. and the residual heavy fraction 104 comprisinghydrocarbons boiling above 370° C. In one or more embodiments and withreference to FIG. 4 , the first fractionator 152 separates the stream ofplastic pyrolysis oil 102 into the plastic pyrolysis naphtha stream 203including hydrocarbons boiling in the range of 36 to 110° C., theplastic pyrolysis second distillate stream 303 including hydrocarbonsboiling in the range of 110 to 370° C., and the residual heavy fraction104 comprising hydrocarbons boiling above 370° C. In variousembodiments, the plastic pyrolysis naphtha stream 203 and the plasticpyrolysis second distillate stream 303 are separated based onfractionation at a hydrocarbon boiling point of 80 to 90° C.commensurate with C6 naphtha, 110 to 120° C. commensurate with C7naphtha, 135 to 145° C. commensurate with C8 naphtha, approximately 85°C., approximately 116° C., or approximately 140° C.

It is noted that when the plastic feedstock includes polymers thatcontain sulfur, chlorine, or fluorine, the plastic pyrolysis oil 102 maybe hydrotreated to remove such heteroatoms. The pretreatment may becompleted before or after the first fractionator 152, if present.

Aromatization Unit

An aromatization unit 154 is provided which is operable to convert oneor more nonaromatic precursors into aromatics to generate a stream withincreased aromatic content. In accordance with the various embodiments,the aromatization unit 154 may be provided in various configurations. Inaccordance with each configuration, the aromatization unit 154 includesat least one aromatization reactor with an aromatization catalystdisposed therein operable to generate a liquid product stream withincreased aromatics content. With reference to FIG. 1 , in one or moreembodiments, the aromatization unit 154 is provided in fluidcommunication with the stream of plastic pyrolysis oil 102. In one ormore further embodiments, and with reference to FIGS. 2 and 3 , thearomatization unit 154 is provided in fluid communication with the firstdistillate fraction 103 generated by the first fractionator 152. In yetone or more further embodiments, and with reference to FIG. 4 , wherethe first distillate fraction is further separated into the plasticpyrolysis naphtha stream 203 and the plastic pyrolysis second distillatestream 303, the aromatization unit 154 is provided as the naphthaaromatization unit 254 in fluid communication with the plastic pyrolysisnaphtha stream 203 generated by the first fractionator 152 and as thesecond distillate aromatization unit 354 in fluid communication with theplastic pyrolysis second distillate stream 303 generated by the firstfractionator 152.

In accordance with the system configuration as illustrated in FIG. 1where the plastic pyrolysis oil 102 is passed directly to thearomatization unit 154, the plastic pyrolysis oil 102 is converted tothe aromatic rich stream 107 in an aromatization reactor 155 provided aspart of the aromatization unit 154.

In accordance with the system configuration as illustrated in FIGS. 2and 3 where the first fractionator 152 is positioned in the flow pathbetween the plastic pyrolysis unit 151 and the aromatization unit 154,the first distillate fraction 103 is converted to the aromatic richstream 107 in the aromatization unit 154. Specifically, in accordancewith FIG. 2 , the first distillate fraction 103 may be directlyconverted to the aromatic rich stream 107 in an aromatization reactor155 provided as part of the aromatization unit 154. Similarly, inaccordance with FIG. 3 , the first distillate fraction 103 may beconverted to the aromatic rich stream 107 in a two-step operationcomprising di-olefin removal in a selective hydrogenation unit 156followed by aromatization in the aromatization reactor 155 provided assub-units of the aromatization unit 154.

In accordance with the system configuration as illustrated in FIG. 4where the first fractionator 152 provides the separate plastic pyrolysisnaphtha stream 203 and plastic pyrolysis second distillate stream 303and is positioned in the flow path between the plastic pyrolysis unit151 and the aromatization unit 154, the plastic pyrolysis naphtha stream203 is converted to a first aromatic rich stream 207 in the naphthaaromatization unit 254 and the plastic pyrolysis second distillatestream 303 is converted to a second aromatic rich stream 307 in thesecond distillate aromatization unit 354. Specifically, the plasticpyrolysis naphtha stream 203 may be converted to the first aromatic richstream 207 in a two-step operation comprising di-olefin removal in anaphtha selective hydrogenation unit 256 followed by aromatization in anaphtha aromatization reactor 255 provided as sub-units of the naphthaaromatization unit 254. Similarly, the plastic pyrolysis seconddistillate stream 303 may be converted to the second aromatic richstream 307 in a two-step operation comprising di-olefin removal in asecond distillate selective hydrogenation unit 356 followed byaromatization in a second distillate aromatization reactor 355 providedas sub-units of the second distillate aromatization unit 354.

The catalytic bed reactor of the aromatization unit 154, provided as thearomatization reactor 155, the naphtha aromatization reactor 255, or thesecond distillate aromatization reactor 355 in accordance with variousembodiments, may operate as a fixed bed reactor in one or moreembodiments. In further embodiments, the catalytic bed reactor of thearomatization unit 154 may operate as a moving bed reactor.

The aromatization catalyst may be selected to efficiently aromatize thefeed stream to the aromatization unit 154. Specifically, thearomatization catalyst may be selected to efficiently aromatize theplastic pyrolysis oil stream 102 from the plastic pyrolysis unit 151 inaccordance with the embodiments of FIG. 1 , to efficiently aromatize thefirst distillate fraction 103 from the first fractionator 152 inaccordance with the embodiments of FIGS. 2 and 3 , and to efficientlyaromatize the plastic pyrolysis naphtha stream 203 from the firstfractionator 152 and the plastic pyrolysis second distillate stream 303from the first fractionator 152 in accordance with the embodiment ofFIG. 4 . It will be appreciated that the aromatization catalyst may beselected to optimize performance based on if the feed stream to thearomatization unit 154 is the plastic pyrolysis oil stream 102 from theplastic pyrolysis unit 151, the first distillate fraction 103 from thefirst fractionator 152, the plastic pyrolysis naphtha stream 203 fromthe first fractionator 152, or the plastic pyrolysis second distillatestream 303 from the first fractionator 152.

In one or more embodiments, the aromatization catalyst comprises a shapeselective zeolite. In various embodiments, the shape selective zeolitemay be selected from medium pore zeolite such as pentasil-type ZSM-5zeolite, large pore zeolite such as zeolite omega and SAPO-5 zeolite,small pore zeolite such as SAPO-34 zeolite, mesoporous zeolite such asSAPO-11 zeolite, and combinations thereof.

It will be appreciated that while zeolite is the active phase of thearomatization catalyst pure zeolite can't be formed into a catalystparticle. As such, in one or more embodiments, the zeolite content ofthe aromatization catalyst may range from 5 wt. % to 80 wt. % withbinders and other components forming the remainder of the aromatizationcatalyst. In various further embodiments, the aromatization catalystcomprises from 5 wt. % to 70 wt. % zeolite, from 5 wt. % to 60 wt. %zeolite, from 10 wt. % to 80 wt. % zeolite, from 20 wt. % to 80 wt. %zeolite, or from 30 wt. % to 50 wt. % zeolite.

In accordance with various embodiments, the aromatization catalyst mayinclude a metal oxide component dispersed on the surfaces of a zeolitesupport. The metal oxide component may include one or more oxides ofmetal elements selected from groups 4 to 13 of the International Unionof Pure and Applied Chemistry (IUPAC) periodic table, such as groups 8to 13 of the IUPAC periodic table. In one or more embodiments, the metalelement of the one or more metal oxides may be a metal element selectedfrom groups 4 to 13 and periods 4 to 6 of the IUPAC periodic table, suchas period 4 of the periodic table. The metal element of the metal oxidemay include, but is not limited to, titanium, vanadium, chromium,manganese, iron, cobalt, nickel, copper, zinc, gallium, zirconium,molybdenum, palladium, silver, hafnium, tungsten, platinum, gold, orcombinations of these metal elements. In one or more embodiments, themetal element of the one or more metal oxides may include zinc,zirconium, gallium, or combinations of these metals. In one or moreembodiments, the metal oxide may be gallium oxide.

In one or more embodiments the aromatization catalyst may comprise agallium modified H-MFI type zeolite. Specifically, the aromatizationcatalyst may comprise a catalyst formed from gallium incorporated intoan H-MFI type zeolite. Such a catalyst may comprise from 1 to 5 weightpercent gallium (Ga) based on the total catalyst. For example, invarious embodiments, the gallium modified H-MFI type zeolite catalystmay comprise from 1 to 4 weight percent gallium, 1 to 3 weight percentgallium, 1.5 to 2.5 weight percent gallium, 1.8 to 2.2 weight percentgallium, or approximately 2 weight percent gallium. It will beappreciated that integration of gallium at other ratios encompassed bythe broadest ranges are also envisioned but not explicitly delineatedfor brevity. As previously indicted, in various embodiments, the galliummay be substituted with an alternative metal element while maintainingthe remaining parameters of the disclosed gallium modified H-MFI typezeolite. In various embodiments, the silica to alumina ratio of theH-MFI type zeolite may vary from 20 to 100, 20 to 80, 20 to 50, or 20 to30.

In one or more embodiments and in accordance with the variousconfigurations, the plastic pyrolysis oil stream 102 from the plasticpyrolysis unit 151, the first distillate fraction 103 from the firstfractionator 152, the plastic pyrolysis naphtha stream 203 from thefirst fractionator 152, or the plastic pyrolysis second distillatestream 303 from the first fractionator 152 is provided to thearomatization unit 154 at a liquid space velocity (LHSV) of 0.5 to 5h⁻¹. In various further embodiments, the plastic pyrolysis oil stream102, the first distillate fraction 103, the plastic pyrolysis naphthastream 203, or the plastic pyrolysis second distillate stream 303 isprovided to the aromatization unit 154 at a LHSV of 0.5 to 4 h⁻¹, 0.5 to3 h⁻¹, 0.5 to 2 h⁻¹, 0.8 to 2 h⁻¹, 1 to 2 h⁻¹, or approximately 1 h⁻¹.It will be appreciated that greater LHSV results in low aromatics yieldwhile lesser LHSV favors formation of less desirable heavy aromatics.

In one or more embodiments and in accordance with the variousconfigurations, the aromatization reactor 155, the naphtha aromatizationreactor 255, or the second distillate aromatization reactor 355 may beoperated at a reaction temperature of 450 to 600° C. In variousembodiments, the aromatization reactor 155, the naphtha aromatizationreactor 255, or the second distillate aromatization reactor 355 may beoperated at a reaction temperature of 450 to 575° C., 500 to 600° C.,500 to 550° C., or approximately 550° C. It will be appreciated thatlesser temperature leads to lesser conversion while greater temperatureresults in faster catalyst deactivation.

In one or more embodiments and in accordance with the variousconfigurations, the second reactor 20 may be operated at a pressure of 1to 5 bar, 1 to 4 bar, 1 to 3 bar, or approximately 1 bar. It will beappreciated that lesser pressure favors aromatization reaction, but aminimum level of positive pressure is needed for practical operation.

Selective Hydrogenation Unit

In one or more embodiments and with reference to FIG. 3 , thearomatization unit 154 further comprises a selective hydrogenation unit156 configured and operated to remove di-olefins by hydrogenation fromthe first distillate fraction 103 to produce a first product stream ofdediolefinized plastic pyrolysis first distillate 106. As such, thedediolefinized plastic pyrolysis first distillate 106 is provided to thearomatization reactor 155 to generate the aromatics rich stream 107. Itwill be appreciated that in one or more embodiments di-olefins areremoved completely from the first distillate fraction 103. For purposesof the present disclosure the term “removed completely” means di-olefinswere reduced to less than 1 weight percent, less than 0.1 weightpercent, less than 0.01 weight percent, less than 0.001 weight percent,or less than 0.0001 weight percent.

In one or more embodiments, the selective hydrogenation unit 156 may bea fixed bed reactor in combination with any known hydrogenationcatalyst. However, the selective hydrogenation unit 156 is not intendedto be limited to any specific type of reactor.

In one or more embodiments, the selective hydrogenation unit 156includes a first hydrogenation catalyst. The first hydrogenationcatalyst may comprise a nickel catalyst on one or more of an aluminasupport, a silica support, and a titania support. For example, the firsthydrogenation catalyst may comprise nickel catalyst on an aluminasupport or nickel-molybdenum (Ni—Mo) catalyst in an alumina support.

In one or more embodiments, the selective hydrogenation unit 156 isoperated at a temperature of 150 to 210° C. In various furtherembodiments, the selective hydrogenation unit 156 is operated at atemperature of 150 to 200° C., 150 to 190° C., 150 to 180° C., orapproximately 175° C.

In one or more embodiments, the selective hydrogenation unit 156 isoperated at a hydrogen pressure at the inlet of 10 to 25 bar. In variousfurther embodiments, the selective hydrogenation unit 156 is operated ata hydrogen pressure at the inlet of 10 to 25 bar, 12 to 22 bar, 15 to 20bar, or approximately 17 bar.

In one or more embodiments, the selective hydrogenation unit 156 isoperated at a liquid hourly space velocity (LHSV) of 1 to 5 inversehours (h⁻¹). In various further embodiments, the selective hydrogenationunit 156 is operated at an LHSV of 1 to 4 h⁻¹, 1 to 3 h⁻¹, orapproximately 2 h.

In one or more embodiments, the selective hydrogenation unit 156 isoperated at a hydrogen to oil ratio of 50 to 300 standard cubic metersper cubic meter (Sm³/m³). One skilled in the art will appreciate thatstandard cubic meters are measured at a temperature of 15° C. andpressure of 1.01325 bar. In various further embodiments, the selectivehydrogenation unit 156 is operated at a hydrogen to oil ratio of 60 to250 Sm³/m³, 65 to 180 Sm³/m³, 70 to 110 Sm³/m³, or 70 to 90 Sm³/m³.

In one or more embodiments and with reference to FIG. 4 , where thefirst fractionator 152 further separates the first distillate fractioninto a plastic pyrolysis naphtha stream 203 and a plastic pyrolysissecond distillate stream 303 which are provided to the naphthaaromatization unit 254 and the second distillate aromatization unit 354respectively, each of the naphtha aromatization unit 254 and the seconddistillate aromatization unit 354 may include an associated selectivehydrogenation unit. Specifically, the naphtha aromatization unit 254further comprises a naphtha selective hydrogenation unit 256 configuredand operated to remove di-olefins by hydrogenation from the plasticpyrolysis naphtha stream 203 to produce a second product stream ofdedioletinized plastic pyrolysis naphtha 206. As such, thedediolefinized plastic pyrolysis naphtha 206 is provided to the naphthaaromatization reactor 255 to generate the first aromatic rich stream207. Similarly, the second distillate aromatization unit 354 furthercomprises a second distillate selective hydrogenation unit 356configured and operated to remove di-olefins by hydrogenation from theplastic pyrolysis second distillate stream 303 to produce a thirdproduct stream of dediolefinized plastic pyrolysis second distillate306. As such, the dediolefinized plastic pyrolysis second distillate 306is provided to the second distillate aromatization reactor 355 togenerate the second aromatic rich stream 307. The first aromatic richstream 207 and the second aromatic rich stream 307 are provided in fluidcommunication with the aromatic recovery complex 157 in lieu of thearomatic rich stream 107.

It will be appreciated that in one or more embodiments di-olefins areremoved completely from the plastic pyrolysis naphtha stream 203.Similarly, it will be appreciated that in one or more embodimentsdi-olefins are removed completely from the plastic pyrolysis seconddistillate stream 303. For purposes of the present disclosure the term“removed completely” means di-olefins were reduced to less than 1 weightpercent, less than 0.1 weight percent, less than 0.01 weight percent,less than 0.001 weight percent, or less than 0.0001 weight percent.

In one or more embodiments, the naphtha selective hydrogenation unit 256may be a fixed bed reactor in combination with any known hydrogenationcatalyst and the second distillate selective hydrogenation unit 356 mayalso be a fixed bed reactor in combination with any known hydrogenationcatalyst. However, the naphtha selective hydrogenation unit 256 and thesecond distillate selective hydrogenation unit 356 are not intended tobe limited to any specific type of reactor.

In one or more embodiments, the naphtha selective hydrogenation unit 256includes a second hydrogenation catalyst. The second hydrogenationcatalyst may comprise a nickel catalyst on one or more of an aluminasupport, a silica support, and a titania support. For example, thesecond hydrogenation catalyst may comprise nickel catalyst on an aluminasupport or nickel-molybdenum (Ni—Mo) catalyst in an alumina support.

Similarly, in one or more embodiments, the second distillate selectivehydrogenation unit 356 includes a third hydrogenation catalyst. Thethird hydrogenation catalyst may comprise a nickel catalyst on one ormore of an alumina support, a silica support, and a titania support. Forexample, the third hydrogenation catalyst may comprise nickel catalyston an alumina support or nickel-molybdenum (Ni—Mo) catalyst in analumina support.

In various embodiments, the first hydrogenation catalyst, the secondhydrogenation catalyst, and the third hydrogenation may be the same ordifferent. For example, the second hydrogenation catalyst may be thesame as the third hydrogenation catalyst in one or more embodiments butdifferent in one or more further embodiments.

In one or more embodiments, the naphtha selective hydrogenation unit 256is operated at a temperature of 150 to 210° C. In various furtherembodiments, the naphtha selective hydrogenation unit 256 is operated ata temperature of 150 to 200° C., 150 to 190° C., 150 to 180° C., orapproximately 175° C.

In one or more embodiments, the second distillate selectivehydrogenation unit 356 is operated at a temperature of 150 to 210° C. Invarious further embodiments, the second distillate selectivehydrogenation unit 356 is operated at a temperature of 150 to 200° C.,150 to 190° C., 150 to 180° C., or approximately 175° C.

In one or more embodiments, the naphtha selective hydrogenation unit 256is operated at a hydrogen pressure at the inlet of 10 to 25 bar. Invarious further embodiments, the naphtha selective hydrogenation unit256 is operated at a hydrogen pressure at the inlet of 10 to 25 bar, 12to 22 bar, 15 to 20 bar, or approximately 17 bar.

In one or more embodiments, the second distillate selectivehydrogenation unit 356 is operated at a hydrogen pressure at the inletof 10 to 25 bar. In various further embodiments, the second distillateselective hydrogenation unit 356 is operated at a hydrogen pressure atthe inlet of 10 to 25 bar, 12 to 22 bar, 15 to 20 bar, or approximately17 bar.

In one or more embodiments, the naphtha selective hydrogenation unit 256is operated at a liquid hourly space velocity (LHSV) of 1 to 5 inversehours (h). In various further embodiments, the naphtha selectivehydrogenation unit 256 is operated at an LHSV of 1 to 4 h⁻¹, 1 to 3 h⁻¹,or approximately 2 h⁻¹.

In one or more embodiments, the second distillate selectivehydrogenation unit 356 is operated at a liquid hourly space velocity(LHSV) of 1 to 5 inverse hours (h⁻¹). In various further embodiments,the second distillate selective hydrogenation unit 356 is operated at anLHSV of 1 to 4 h⁻¹, 1 to 3 h⁻¹, or approximately 2 h⁻¹.

In one or more embodiments, the naphtha selective hydrogenation unit 256is operated at a hydrogen recycle rate of 50 to 300 standard cubicmeters per cubic meter (Sm³/m³). One skilled in the art will appreciatethat standard cubic meters are measured at a temperature of 15° C. andpressure of 1.01325 bar. In various further embodiments, the naphthaselective hydrogenation unit 256 is operated at a hydrogen recycle rateof 60 to 250 Sm³/m³, 65 to 180 Sm³/m³, 70 to 110 Sm³/m³, or 70 to 90Sm³/m³.

In one or more embodiments, the second distillate selectivehydrogenation unit 356 is operated at a hydrogen recycle rate of 50 to300 standard cubic meters per cubic meter (Sm³/m³). One skilled in theart will appreciate that standard cubic meters are measured at atemperature of 15° C. and pressure of 1.01325 bar. In various furtherembodiments, the second distillate selective hydrogenation unit 356 isoperated at a hydrogen recycle rate of 60 to 250 Sm³/m³, 65 to 180Sm³/m³, 70 to 110 Sm/m³, or 70 to 90 Sm³/m³.

Aromatic Recovery Complex

In one or more embodiments, the aromatic rich stream 107 is passed tothe aromatic recovery complex 157 to separate the aromatic rich stream107 into the BTX fraction 109, the gasoline blending fraction 110, thegas fraction 108, and the aromatic bottoms fraction 111. The BTXfraction 109 consists of benzene, toluene and mixed xylenes. The gasfraction 108 comprises hydrogen and C1-C4 hydrocarbons. The aromaticbottoms fraction 111 comprises hydrocarbons boiling above 180° C. Thegasoline blending fraction 110 comprises aliphatic hydrocarbons with aboiling range from C5 hydrocarbons up to the aromatic bottoms fraction111.

Various systems and techniques may be utilized in the aromatics recoverycomplex 157 for separating the aromatics rich stream 107 into variousfractions and the present disclosure is not intended to be limited innature to the specific arrangement of the aromatics recovery complex157. Generally, the aromatics recovery complex 157 produces thearomatics rich stream 107 into the BTX fraction 109, the gasolineblending fraction 110, the gas fraction 108, and the aromatic bottomsfraction 111. While the BTX fraction 109 is illustrated as a singlestream for reduced complexity in each of the Figures, it will beappreciated that the BTX fraction 109 may be further separated intoindividual steams of benzene, toluene and mixed xylenes within thearomatics recovery complex 157.

There are many configurations of aromatics recovery complexes ingeneral. In one or more embodiments, the aromatics recovery complex 157may include, for example, a dehexanizer distillation column that removeslighter components and discharges a bottoms product stream. The bottomsproduct stream may be fed to a benzene distillation column that removesbenzene overhead and discharges a bottoms stream having, for example,toluene, mixed xylenes, ethyl benzene, and C9+ aromatic compounds. Insome instances, the overhead discharge may enter absorber and strippercolumns to purify the benzene. The bottoms stream from the benzenedistillation column may be processed in absorber and stripper columns toremove light components and further in distillation columns. Theaforementioned absorber and stripper columns may involve solventextraction.

This bottoms stream from the benzene distillation column may ultimatelybe processed in distillation columns to separate and recover toluene andvarious mixed xylenes. The distillation columns may include a toluenedistillation column(s) and a xylene distillation column(s). A toluenedistillation column may separate and discharge toluene overhead. Thexylene distillation column may receive the bottoms discharge from thetoluene distillation column, separate and discharge mixed xylenesoverhead and discharge a heavy aromatics (C9+) bottoms stream, such asthe aromatic bottoms fraction 111.

With reference to FIGS. 3 and 4 , in one or more embodiments, apretreater (not shown) is provided to remove contaminants from thestream of plastic pyrolysis oil 102. Specifically, the pretreater mayremove sulfur (S), nitrogen (N), oxygen (O), chlorine (C1), orcombinations of the same from the stream of plastic pyrolysis oil 102.The pretreater may be a conventional hydrotreating system configured toremove the hydrocarbons with heteroatoms. Further, dechlorination may beachieved in the pretreater with ammonium chloride formed in the reactionwater washed after the hydrotreating system. It is noted that waterwashing removes ammonium sulfide formed between hydrogen sulfide andammonia in addition to the ammonium chloride formed.

In one or more embodiments, the pretreater is positioned subsequent tothe first fractionator 152, if present, to remove contaminants from oneor more of the first distillate fraction 103, the plastic pyrolysisnaphtha stream 203, and the plastic pyrolysis second distillate stream303 prior to introduction to the aromatization unit 154.

Removal of contaminants is desirable as nitrogen-containing species canpoison the aromatization catalyst, chlorine causes metallurgical issueand therefore must meet the design specification of the processingunits, and sulfur removal is desirable to meet final fuelspecifications.

In one or more embodiments, the residual heavy fraction 104 comprisinghydrocarbons boiling above 370° C. is provided to a demetallizationoperation 153 to remove metallic constituents from the residual heavyfraction 104 and generate a demetallized residual heavy fraction stream105.

In one or more embodiments, the demetallization operation 153 may becatalytic hydrodemetallization. U.S. Pat. No. 8,491,779, incorporated byreference, teaches the integration of catalytic hydrodemetallization(HDM) into a refinery process. The HDM step is carried out in thepresence of a catalyst and hydrogen. Further, in one or moreembodiments, the hydrogen that is used can come from a downstream step.The HDM is generally carried out at 370 to 415° C. and pressure of 30 to200 bars. Also, see U.S. Pat. No. 5,417,846, incorporated by reference,teaching HDM, as well as U.S. Pat. Nos. 4,976,848; 4,657,664; 4,166,026;and 3,891,541, all of which are incorporated by reference.

In one or more embodiments, the demetallization operation 153 may besolvent deasphalting. The process of solvent deasphalting results in themetal containing hydrocarbons of the processed streaming end up in anasphaltenes stream of a solvent deasphalting unit. U.S. Pat. No.7,566,394, incorporated by reference, teaches details of a solventdeasphalting process.

Having described the system for processing mixed plastics into plasticpyrolysis products, it is expressly indicated that the associated methodof producing pyrolysis products from a mixed plastics stream using thesame is also envisioned. The method includes conducting pyrolysis of aplastic feedstock to produce a stream of plastic pyrolysis oil 102,feeding the plastic pyrolysis oil 102 to an aromatization unit 154comprising an aromatization reactor 155 with an aromatization catalystdisposed therein to generate an aromatics rich stream 107, and passingthe aromatics rich stream 107 to an aromatics recovery complex 157 toseparate the aromatics rich stream 107 into a BTX fraction 109, agasoline blending fraction 110, a gas fraction 108 comprising hydrogenand C1-C4 hydrocarbons, and an aromatic bottoms fraction 111 comprisinghydrocarbons boiling above 180° C. The BTX fraction 109 consists ofbenzene, toluene and mixed xylenes and the gasoline blending fraction110 comprises aliphatic hydrocarbons with a boiling range from C5hydrocarbon up to the aromatic bottoms fraction.

The method of producing pyrolysis products from a mixed plastics streammay also include feeding the plastic pyrolysis oil 102 to a firstfractionator 152 to separate the plastic pyrolysis oil 102 into a firstdistillate fraction 103 including hydrocarbons boiling in the range of36 to 370° C. and a residual heavy fraction 104 comprising hydrocarbonsboiling above 370° C. In such arrangement, the method includes feedingthe first distillate fraction 103 to the aromatization unit in lieu ofan entirety of the plastic pyrolysis oil 102. The first fractionator mayfurther separate the first distillate fraction 103 into a plasticpyrolysis naphtha stream 203 and a plastic pyrolysis second distillatestream 303. In such arrangement the aromatization unit is split into anaphtha aromatization unit 254 comprising a naphtha aromatizationreactor 255 fed by the plastic pyrolysis naphtha stream 203 and a seconddistillate aromatization unit 354 comprising a second distillatearomatization reactor 355 fed by the plastic pyrolysis second distillatestream 303.

In accordance with one or more embodiments of a method of producingpyrolysis products from a mixed plastics stream the aromatization unit154 may further comprises a selective hydrogenation unit 156 configuredand operated to remove di-olefins by hydrogenation from the firstdistillate fraction 103 to produce a first product stream ofdediolefinized plastic pyrolysis first distillate 106. In accordancewith such arrangement the dediolefinized plastic pyrolysis firstdistillate 106 is provided to the aromatization reactor 155 to generatethe aromatic rich stream 107.

Further, in accordance with one or more embodiments of a method ofproducing pyrolysis products from a mixed plastics stream the naphthaaromatization unit 254 may further comprises a naphtha selectivehydrogenation unit 256 configured and operated to remove di-olefins byhydrogenation from the plastic pyrolysis naphtha stream 203 to produce asecond product stream of dediolefinized plastic pyrolysis naphtha 206.Similarly, the second distillate aromatization unit 354 may furthercomprises a second distillate selective hydrogenation unit 356configured and operated to remove di-olefins by hydrogenation from theplastic pyrolysis second distillate stream 303 to produce a thirdproduct stream of dediolefinized plastic pyrolysis second distillate306. In accordance with such arrangement the dediolefinized plasticpyrolysis naphtha 206 is provided to the naphtha aromatization reactor255 to generate a first aromatics rich stream 207 and the dediolefinizedplastic pyrolysis second distillate 306 is provided to the seconddistillate aromatization reactor 355 to generate a second aromatics richstream 307 with the first aromatic rich stream 207 and the secondaromatics rich stream 307 provided to the aromatics recovery complex 157in lieu of the aromatics rich stream 107.

In one or more embodiments, the system for processing of mixed plasticsinto plastic pyrolysis products may be integrated with a conventionalrefinery and other refining processes. For purposes of this disclosure aconventional refinery is meant as to reference an existing refiningoperation for processing crude oil into a plurality of useful products.

In one or more embodiments, integration with the conventional refinerymay further include providing the demetallized residual heavy fractionstream 105 to one or more of a residual heavy fraction selectivehydrogenation unit, a hydrocracking unit, and a residue hydroprocessingunit provided in the conventional refinery. Details of such systems arenot provided for conciseness, but are known to those skilled in the art.

In one or more embodiments, integration with the conventional refinerymay further include providing the residual heavy fraction 104 from thefirst fractionator 152 directly to one or more of a delayed coking unit,a gasification unit, and a solvent desphalting unit provided in theconventional refinery without preprocessing in the demetallizationoperation 153. Details of such systems are not provided for conciseness,but are known to those skilled in the art.

EXAMPLES

The following examples illustrate features of the present disclosure butare not intended to limit the scope of the disclosure.

To demonstrate the utility of the methods of producing pyrolysisproducts from a mixed plastics stream in accordance with the presentdisclosure representative testing was completed. Specifically, a BTXfraction 109, a gasoline blending fraction 110, a gas fraction 108, andan aromatic bottoms fraction 111 were generated in accordance withembodiments of the present disclosure.

A plastic feed comprising a mixture of HDPE, LDPE, PP, LLDPE, PS, andPET was provided to a plastic pyrolysis unit 151 and processed togenerate a stream of plastic pyrolysis oil 102 in accordance with thepresent disclosure. The properties and composition of the plasticpyrolysis oil 102 are shown in Tables 2, 3, and 4.

TABLE 2 Example Plastic Pyrolysis Oil Composition Property/CompositionUnit Value Density kg/m³ 790 Chlorine ppmw 130 Nitrogen ppmw 1139 Sulfurppmw 82 Oxygen ppmw 1562 Metals ppmw 65 Di-olefins W % 9.4 Mono-OlefinsW % 50.0

TABLE 3 Example Plastic Pyrolysis Oil Composition Composition Unit ValueNaphtha (36-110° C.) W % 14.0 Second Distillate (110-370° C.) W % 75.6Residual Heavy Fraction (370° C.+) W % 10.4

TABLE 4 Example Plastic Pyrolysis Oil Naphtha Composition Iso N- Mono-Di- C# Paraffin Paraffin Paraffin Olefin Aromatic olefin Total 5 9.700.09 0.00 3.92 0.00 0.71 14.42 6 9.43 0.56 0.00 27.71 4.66 0.49 42.86 715.32 1.83 0.00 16.63 8.94 0.00 42.72 Total 34.45 2.48 0.00 48.26 13.601.20 100.00

After pyrolysis, the generated plastic pyrolysis oil was aromatized in afixed-bed unit in accordance with embodiments of the present disclosure.Specifically, the plastic pyrolysis oil was provided to a fixed bedaromatization reactor loaded with a gallium doped HZSM-5 zeolitecatalyst having a silica to alumina ratio of 30. The aromatizationreactor was operated at 550° C. and WHSV of 1 hr⁻¹ for 5 hours. Thespecific operating conditions are provided in Table 5. At operatinghours 2, 3, 4, and 5 samples of the effluent from the aromatizationreactor representative of the aromatic rich stream 107 were measured towith PIONA analysis via gas chromatography to determine theircomposition. The composition of the effluent after 2 hours, 3 hours, 4,hours, and 5 hours is provided in Table 6.

TABLE 5 Aromatization Reactor Operating Conditions Parameter unit valueTemperature ° C. 550 Pressure Bar  1 WHSV hr⁻¹  1 Catalyst gallium dopedHZSM-5 zeolite

TABLE 6 Product yields from aromatization reactor testing Time on Stream2 hours 3 hours 4 hours 5 hours Conversion (%) 100.00 100.00 100.00100.00 C1 (wt. %) 1.29 1.68 1.74 1.44 C2 (wt. %) 0.78 1.17 1.34 1.71 C2(wt. %) 0.13 0.14 0.14 0.27 C3 + C4 (wt. %) 19.96 20.61 22.41 23.87 GasParaffins & Olefins 22.16 23.59 25.63 27.28 C5 (wt. %) 0.00 0.00 0.000.00 C6 (wt. %) 0.00 0.00 0.00 0.00 C7 (wt. %) 0.00 0.00 0.00 0.00 C8(wt. %) 0.00 0.00 0.00 0.00 C9 + (wt. %) 0.00 0.00 0.00 0.00 LiquidParaffins & 0.00 0.00 0.00 0.00 Olefins Benzene (wt. %) 35.78 34.8234.51 33.43 Toluene (wt. %) 36.08 36.13 33.66 32.95 Ethyl Benzene (wt.%) 0.10 0.04 0.03 0.05 5 1,2-Xylene (wt. %) 1.15 0.96 1.13 1.131,3-Xylene (wt. %) 2.81 2.41 2.46 2.38 1,4-Xylene (wt. %) 1.38 1.21 1.161.12 Total BTEX (wt. %) 77.30 75.58 72.95 71.06 1,3,5-trimethyl benzene0.07 0.07 0.12 0.11 (wt. %) 1,2,4-trimethyl benzene 0.18 0.21 0.32 0.38(wt. %) 1,4-methyl-i- 0.30 0.54 0.98 1.16 propylbenzene (wt. %) TotalC9+ Aromatics 0.55 0.83 1.42 1.66 (wt. %) Total Aromatics 77.84 76.4174.37 72.72 Total 100.00 100.00 100.00 100.00 RON 114.9 115 114.8 114.9MON 101.1 101.2 101.2 101.4

The prevalence of BTX (benzene, toluene, xylenes) in the generatedproduct stream is apparent from a review of Table 6. In particular it isnoted that on average the plastic pyrolysis oil generated 34.6 wt %,34.7 wt % and 4.8 wt % benzene, toluene and xylenes, respectively for anaverage total generation of BTX of 77.2 wt % of the generated product.Further, it is noted that the research octane number (RON) of the totalliquid products was an average of 114.9 and the motor octane number(MON) of the total liquid products was an average of 101.2, indicatingthat the product is a high octane gasoline.

It will be appreciated that in instances where pyrolysis oil is directlyfed to an aromatization unit without the di-olefin removal procedures,the di-olefins would deactivate the catalyst after a short period oftime as the di-olefins are reactive and would polymerize. As such, it isimpractical to prepare a comparative example where a stream of untreatedpyrolysis oil is processed.

It should now be understood the various aspects of the method ofproducing pyrolysis products from a mixed plastics stream and associatedsystem for processing mixed plastics into plastic pyrolysis products aredescribed and such aspects may be utilized in conjunction with variousother aspects.

According to a first aspect, a method of producing pyrolysis productsfrom a mixed plastics stream includes (a) conducting pyrolysis of aplastic feedstock to produce a stream of plastic pyrolysis oil; (b)feeding the plastic pyrolysis oil to an aromatization unit comprising anaromatization reactor with an aromatization catalyst disposed therein togenerate an aromatics rich stream; and (c) passing the aromatics richstream to an aromatics recovery complex to separate the aromatics richstream into a BTX fraction, a gasoline blending fraction, a gas fractioncomprising hydrogen and C1-C4 hydrocarbons, and an aromatic bottomsfraction comprising hydrocarbons boiling above 180° C. The BTX fractionconsists of benzene, toluene and mixed xylenes and the gasoline blendingfraction comprises aliphatic hydrocarbons with a boiling range from C5hydrocarbons up to the aromatic bottoms fraction.

A second aspect includes the method of the first aspect in which themethod further comprises feeding the plastic pyrolysis oil to a firstfractionator to separate the plastic pyrolysis oil into a firstdistillate fraction comprising hydrocarbons boiling in the range of 36to 370° C. and a residual heavy fraction comprising hydrocarbons boilingabove 370° C., and feeding the first distillate fraction to thearomatization unit in lieu of an entirety of the plastic pyrolysis oil.

A third aspect includes the method of the second aspect in which thearomatization unit further comprises a selective hydrogenation unitconfigured and operated to remove di-olefins by hydrogenation from thefirst distillate fraction to produce a first product stream ofdedioletinized plastic pyrolysis first distillate, where thededioletinized plastic pyrolysis first distillate is provided to thearomatization reactor to generate the aromatics rich stream.

A fourth aspect includes the method of the second in which the firstfractionator further separates the first distillate fraction into aplastic pyrolysis naphtha stream and a plastic pyrolysis seconddistillate stream; and the aromatization unit is split into a naphthaaromatization unit comprising a naphtha aromatization reactor fed by theplastic pyrolysis naphtha stream and a second distillate aromatizationunit comprising a second distillate aromatization reactor fed by theplastic pyrolysis second distillate stream.

A fifth aspect includes the method of the fourth aspect in which theplastic pyrolysis naphtha stream comprises hydrocarbons boiling in therange of 36 to 110° C. and the plastic pyrolysis second distillatestream comprises hydrocarbons boiling in the range of 110 to 370° C.

A sixth aspect includes the method of the fourth or fifth aspect inwhich the naphtha aromatization unit further comprises a naphthaselective hydrogenation unit configured and operated to removedi-olefins by hydrogenation from the plastic pyrolysis naphtha stream toproduce a second product stream of dediolefinized plastic pyrolysisnaphtha and the second distillate aromatization unit further comprises asecond distillate selective hydrogenation unit configured and operatedto remove di-olefins by hydrogenation from the plastic pyrolysis seconddistillate stream to produce a third product stream of dediolefinizedplastic pyrolysis second distillate. The dediolefinized plasticpyrolysis naphtha is provided to the naphtha aromatization reactor togenerate a first aromatics rich stream and the dediolefinized plasticpyrolysis second distillate is provided to the second distillatearomatization reactor to generate a second aromatics rich stream. Thefirst aromatics rich stream and the second aromatic rich stream areprovided to the aromatic recovery complex in lieu of the aromatics richstream.

A seventh aspect includes the method of any of the first through sixthaspects in which the plastic feedstock comprises mixed plastics ofdiffering compositions.

An eighth aspect includes the method of any of the first through seventhaspects in which the method further comprises feeding the residual heavyfraction comprising hydrocarbons boiling above 370° C. to ademetallization operation to remove metallic constituents from theresidual heavy fraction and generate a demetallized residual heavyfraction stream.

A ninth aspect includes the method of the third aspect in which theselective hydrogenation unit includes a hydrogenation catalyst, thehydrogenation catalyst comprising a nickel catalyst on one or more of analumina support, a silica support, and a titania support.

A tenth aspect includes the method of the sixth aspect in which thenaphtha selective hydrogenation unit and the second distillate selectivehydrogenation unit each include a hydrogenation catalyst, thehydrogenation catalyst comprising a nickel catalyst on one or more of analumina support, a silica support, and a titania support.

An eleventh aspect includes the method of the third aspect in which theselective hydrogenation unit is operated at a temperature of 150 to 210°C.

A twelfth aspect includes the method of the sixth aspect in which thenaphtha selective hydrogenation unit and the second distillate selectivehydrogenation unit are operated at a temperature of 150 to 210° C.

A thirteenth aspect includes the method of any of the first throughthird aspects in which the aromatization reactor is operated at atemperature of 450 to 600° C.

A fourteenth aspect includes the method of any of the fourth throughsixth aspects in which the naphtha aromatization reactor and the seconddistillate aromatization reactor are operated at a temperature of 450 to600° C.

A fifteenth aspect includes the method of any of the first throughfourteenth aspects in which the aromatization reactor includes anaromatization catalyst comprising a shape selective zeolite selectedfrom medium pore zeolite, large pore zeolite, small pore zeolite,mesoporous zeolite, and combinations thereof.

A sixteenth aspect includes the method of the fifteenth aspect in whichthe shape selective zeolite is doped with one or more of Zn. Zr. and Ga.

A seventeenth aspect includes the method of the fifteenth or sixteenthaspect in which the aromatization catalyst comprises 5 wt. % to 80 wt. %zeolite.

An eighteenth aspect includes the method of any of the first throughseventeenth aspects in which the pyrolysis of a plastic feedstock isperformed in the presence of a catalyst at a temperature of 300 to 1000°C.

According to a nineteenth aspect a system for processing mixed plasticsinto plastic pyrolysis products includes an inlet stream comprisingmixed plastics; a plastic pyrolysis unit, the plastic pyrolysis unit influid communication with the inlet stream, and operable to generate astream of plastic pyrolysis oil from the inlet stream; an aromatizationunit in fluid communication with the stream of plastic pyrolysis oil,the aromatization unit comprising an aromatization reactor with anaromatization catalyst disposed therein operable to generate anaromatics rich stream; and an aromatics recovery complex in fluidcommunication with the aromatics rich stream, the aromatics recoverycomplex operable to separate the aromatics rich stream into a BTXfraction, a gasoline blending fraction, a gas fraction comprisinghydrogen and C1-C4 hydrocarbons, and an aromatic bottoms fractioncomprising hydrocarbons boiling above 180° C. The BTX fraction consistsof benzene, toluene and mixed xylenes and the gasoline blending fractioncomprises aliphatic hydrocarbons with a boiling range from C5hydrocarbon up to the aromatic bottoms fraction.

A twentieth aspect includes the system of the nineteenth aspect in whichthe system further comprises a first fractionator, the firstfractionator in fluid communication with the stream of plastic pyrolysisoil to separate the plastic pyrolysis oil into a first distillatefraction comprising hydrocarbons boiling in the range of 36 to 370° C.and a residual heavy fraction comprising hydrocarbons boiling above 370°C. with the first distillate fraction in fluid communication with thearomatization unit in lieu of an entirety of the stream of plasticpyrolysis oil.

A twenty-first aspect includes the system of the twentieth aspect inwhich the aromatization unit further comprises a selective hydrogenationunit in fluid communication with the first distillate fraction, theselective hydrogenation unit configured and operated to removedi-olefins by hydrogenation from the first distillate fraction toproduce a first product stream of dediolefinized plastic pyrolysis firstdistillate, where the dediolefinized plastic pyrolysis first distillateis provided in direct communication with the aromatization reactor togenerate the aromatics rich stream.

A twenty-second aspect includes the system of the twentieth aspect inwhich the first fractionator further separates the first distillatefraction into a plastic pyrolysis naphtha stream and a plastic pyrolysissecond distillate stream; and the aromatization unit is split into anaphtha aromatization unit comprising a naphtha aromatization reactorand a second distillate aromatization unit comprising a seconddistillate aromatization reactor.

A twenty-third aspect includes the system of the twenty-second aspect inwhich the plastic pyrolysis naphtha stream comprises hydrocarbonsboiling in the range of 36 to 110° C. and the plastic pyrolysis seconddistillate stream comprises hydrocarbons boiling in the range of 110 to370° C.

A twenty-fourth aspect includes the system of the twenty-second ortwenty-third aspect in which the naphtha aromatization unit furthercomprises a naphtha selective hydrogenation unit in fluid communicationwith the plastic pyrolysis naphtha stream, the naphtha selectivehydrogenation unit configured and operated to remove di-olefins byhydrogenation from the plastic pyrolysis naphtha stream to produce asecond product stream of dediolefinized plastic pyrolysis naphtha, wherethe dediolefinized plastic pyrolysis naphtha is provided in directcommunication with the naphtha aromatization reactor to generate a firstaromatic rich stream; and the second distillate aromatization unitfurther comprises a second distillate selective hydrogenation unit influid communication with the plastic pyrolysis second distillate stream,the second distillate selective hydrogenation unit configured andoperated to remove di-olefins by hydrogenation from the plasticpyrolysis second distillate stream to produce a third product stream ofdediolefinized plastic pyrolysis second distillate, where thedediolefinized plastic pyrolysis second distillate is provided in directcommunication with the second distillate aromatization reactor togenerate a second aromatics rich stream. Further, the first aromaticsrich stream and the second aromatics rich stream are provided in fluidcommunication with the aromatics recovery complex in lieu of thearomatics rich stream.

A twenty-fifth aspect includes the system of any of the nineteenththrough twenty-fourth aspects in which the system further comprises apretreater to remove contaminants from one or more of the plasticpyrolysis oil, the first distillate fraction, the plastic pyrolysisnaphtha stream, and the plastic pyrolysis second distillate stream tointroduction to the aromatization unit 154

It should be apparent to those skilled in the art that variousmodifications and variations can be made to the described embodimentswithout departing from the spirit and scope of the claimed subjectmatter. Thus, it is intended that the specification cover themodifications and variations of the various described embodimentsprovided such modifications and variations come within the scope of theappended claims and their equivalents.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

Throughout this disclosure ranges are provided. It is envisioned thateach discrete value encompassed by the ranges are also included.Additionally, the ranges which may be formed by each discrete valueencompassed by the explicitly disclosed ranges are equally envisioned.For brevity, the same is not explicitly indicated subsequent to eachdisclosed range and the present general indication is provided.

As used in this disclosure and in the appended claims, the words“comprise,” “has,” and “include” and all grammatical variations thereofare each intended to have an open, non-limiting meaning that does notexclude additional elements or steps.

What is claimed is:
 1. A method of producing pyrolysis products from amixed plastics stream, the method comprising: (a) conducting pyrolysisof a plastic feedstock to produce a stream of plastic pyrolysis oil; (b)feeding the plastic pyrolysis oil to a first fractionator to separatethe plastic pyrolysis oil into a first distillate fraction comprisinghydrocarbons boiling in the range of 36 to 370° C. and a residual heavyfraction comprising hydrocarbons boiling above 370° C.; (c) feeding thefirst distillate fraction to an aromatization unit comprising anaromatization reactor with an aromatization catalyst disposed therein togenerate an aromatics rich stream; and (d) passing the aromatics richstream to an aromatics recovery complex to separate the aromatics richstream into a BTX fraction, a gasoline blending fraction, a gas fractioncomprising hydrogen and C1-C4 hydrocarbons, and an aromatic bottomsfraction comprising hydrocarbons boiling above 180° C., where the BTXfraction consists of benzene, toluene and mixed xylenes and the gasolineblending fraction comprises aliphatic hydrocarbons with a boiling rangefrom C5 hydrocarbon up to the aromatic bottoms fraction.
 2. (canceled)3. The method of claim 1, where the aromatization unit further comprisesa selective hydrogenation unit configured and operated to removedi-olefins by hydrogenation from the first distillate fraction toproduce a first product stream of dediolefinized plastic pyrolysis firstdistillate, where the dediolefinized plastic pyrolysis first distillateis provided to the aromatization reactor to generate the aromatics richstream.
 4. The method of claim 1, where the first fractionator furtherseparates the first distillate fraction into a plastic pyrolysis naphthastream and a plastic pyrolysis second distillate stream; and thearomatization unit is split into a naphtha aromatization unit comprisinga naphtha aromatization reactor fed by the plastic pyrolysis naphthastream and a second distillate aromatization unit comprising a seconddistillate aromatization reactor fed by the plastic pyrolysis seconddistillate stream.
 5. The method of claim 4, where the plastic pyrolysisnaphtha stream comprises hydrocarbons boiling in the range of 36 to 110°C. and the plastic pyrolysis second distillate stream compriseshydrocarbons boiling in the range of 110 to 370° C.
 6. The method ofclaim 4, where the naphtha aromatization unit further comprises anaphtha selective hydrogenation unit configured and operated to removedi-olefins by hydrogenation from the plastic pyrolysis naphtha stream toproduce a second product stream of dediolefinized plastic pyrolysisnaphtha and the second distillate aromatization unit further comprises asecond distillate selective hydrogenation unit configured and operatedto remove di-olefins by hydrogenation from the plastic pyrolysis seconddistillate stream to produce a third product stream of dediolefinizedplastic pyrolysis second distillate, where the dediolefinized plasticpyrolysis naphtha is provided to the naphtha aromatization reactor togenerate a first aromatics rich stream and the dediolefinized plasticpyrolysis second distillate is provided to the second distillatearomatization reactor to generate a second aromatics rich stream, wherethe first aromatics rich stream and the second aromatics rich stream areprovided to the aromatics recovery complex in lieu of the aromatics richstream.
 7. The method of claim 1, where the plastic feedstock comprisesmixed plastics of differing compositions.
 8. The method of claim 1,where the method further comprises feeding the residual heavy fractioncomprising hydrocarbons boiling above 370° C. to a demetallizationoperation to remove metallic constituents from the residual heavyfraction and generate a demetallized residual heavy fraction stream. 9.The method of claim 3, where the selective hydrogenation unit includes ahydrogenation catalyst, the hydrogenation catalyst comprising a nickelcatalyst on one or more of an alumina support, a silica support, and atitania support.
 10. The method of claim 6, where the naphtha selectivehydrogenation unit and the second distillate selective hydrogenationunit each include a hydrogenation catalyst, the hydrogenation catalystcomprising a nickel catalyst on one or more of an alumina support, asilica support, and a titania support.
 11. The method of claim 1, wherethe aromatization reactor includes an aromatization catalyst comprisinga shape selective zeolite selected from medium pore zeolite, large porezeolite, small pore zeolite, mesoporous zeolite, and combinationsthereof.
 12. The method of claim 11, where the shape selective zeoliteis doped with a metal modifier selected from one or more of Zn, Zr, andGa.
 13. The method of claim 11, where the aromatization catalystcomprises 5 wt. % to 80 wt. % zeolite.
 14. The method of claim 3, wherethe selective hydrogenation unit is operated at a temperature of 150 to210° C.
 15. The method of claim 6, where the naphtha selectivehydrogenation unit and the second distillate selective hydrogenationunit are operated at a temperature of 150 to 210° C.
 16. The method ofclaim 1, where the aromatization reactor is operated at a temperature of450 to 600° C.
 17. The method of claim 1, where the pyrolysis of aplastic feedstock is performed in the presence of a catalyst at atemperature of 300° C. to 1000° C. 18-23. (canceled)